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FFT a few questions
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FFT a few questions
http://rghost.ru/46459517/image.png <--- Image, Forum use only 400px.
Hello, tell me, why in the translation values in a comprehensive form, the first value in the 2 arrays are not true?
I use Graph, can I use another component (not Graph)to get an array F of stream?
If only Graph use this methode, how create auto get? I use trigger...
How convert array F of data in stream?
Hello, tell me, why in the translation values in a comprehensive form, the first value in the 2 arrays are not true?
I use Graph, can I use another component (not Graph)to get an array F of stream?
If only Graph use this methode, how create auto get? I use trigger...
How convert array F of data in stream?
- borodadada
- Posts: 47
- Joined: Sun Jun 02, 2013 5:58 pm
Re: FFT a few questions
Hi, and welcome to the forum!
The first FFT Bin contains the DC Offset of your waveform. So if your waveform isn't center arround 0, than you'll get really high values there.
I've attached a schematic that shows the effect of a DC-Remover to the FFT. The schematic also demonstrates the difference between the 2 nearly similare primitives "Graph FFT" and "FFT". The "Graph FFT" is unscaled, this means the result values are multiplied by the array length. The "FFT" primitive works with scaled values and that's also why you shouldn't use "Graph FFT" with the "Mag/Phase"primitives, the result wouldn't be correct.
Your way of converting Stream for Float Array is the right way. You have to trigger "get", when you want to update your FFT.
Converting a Float Array to Stream, is a very difficult task. You have to convert the Float Array into a memory (those gray/black rectangle connectors), and then you have to use some kind of waveplayer to play it back. If your goal is Realtime FFT/iFFT, then I've to disappoint you, this is at the moment not possible with primitives. It could be done with Ruby, but nobody done that before.
Regards
Maik
The first FFT Bin contains the DC Offset of your waveform. So if your waveform isn't center arround 0, than you'll get really high values there.
I've attached a schematic that shows the effect of a DC-Remover to the FFT. The schematic also demonstrates the difference between the 2 nearly similare primitives "Graph FFT" and "FFT". The "Graph FFT" is unscaled, this means the result values are multiplied by the array length. The "FFT" primitive works with scaled values and that's also why you shouldn't use "Graph FFT" with the "Mag/Phase"primitives, the result wouldn't be correct.
Your way of converting Stream for Float Array is the right way. You have to trigger "get", when you want to update your FFT.
Converting a Float Array to Stream, is a very difficult task. You have to convert the Float Array into a memory (those gray/black rectangle connectors), and then you have to use some kind of waveplayer to play it back. If your goal is Realtime FFT/iFFT, then I've to disappoint you, this is at the moment not possible with primitives. It could be done with Ruby, but nobody done that before.
Regards
Maik
- Attachments
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- FFT Comparison (MyCo).fsm
- (3.47 KiB) Downloaded 1010 times
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MyCo - Posts: 718
- Joined: Tue Jul 13, 2010 12:33 pm
- Location: Germany
Re: FFT a few questions
Hello MyCo,
Just following along to learn.
The posted .fsm loaded fine ... but when I clicked the 'trigger', FS crashes
Just following along to learn.
The posted .fsm loaded fine ... but when I clicked the 'trigger', FS crashes
- RJHollins
- Posts: 1571
- Joined: Thu Mar 08, 2012 7:58 pm
Re: FFT a few questions
The same here.
Need to take a break? I have something right for you.
Feel free to donate. Thank you for your contribution.
Feel free to donate. Thank you for your contribution.
- tester
- Posts: 1786
- Joined: Wed Jan 18, 2012 10:52 pm
- Location: Poland, internet
Re: FFT a few questions
noticed that too, I reported it already to Malc.
I've attached a schematic that has a workaround for the bug.
I've attached a schematic that has a workaround for the bug.
- Attachments
-
- FFT Comparison2 (MyCo).fsm
- (3.62 KiB) Downloaded 1049 times
-
MyCo - Posts: 718
- Joined: Tue Jul 13, 2010 12:33 pm
- Location: Germany
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